Measurement of positron mobility in Si at 30–300 K

The temperature dependence of positron motion in silicon (Si:[P]=4×${10}^{14}$ ${\mathrm{cm}}^{\mathrm{-}3}$) is studied experimentally by measuring the drift length of positrons in the space-charge region of an Au-Si surface-barrier diode. At 300 K the positron mobility is 110±15 ${\mathrm{cm}}^2$ ${\mathrm{V}}^{\mathrm{-}1}$ ${\mathrm{s}}^{\mathrm{-}1}$, and it increases to 2800±1000 ${\mathrm{cm}}^2$ ${\mathrm{V}}^{\mathrm{-}1}$ ${\mathrm{s}}^{\mathrm{-}1}$ at 30 K. Below 300 K the mobility varies with temperature in accordance with ${\mathit{T}}^{\mathrm{-}3/2}$. This temperature dependence of carrier mobility is typical of scattering from longitudinal-acoustic phonons.